Lock bumping in recent years has become a serious problem in the lock industry, impacting on the reliability and security of pin tumbler locks in particular.
Lock bumping generally involves using a key with a reduced stopper/shoulder and a series of low key cuts. Once such a key is inserted into the key slot, the engaging surface of each pin can be located right up against the side of each cut (as opposed to the middle of each cut). A pre-rotational tension is then applied to the key followed by continuous tapping on the head of the key. These actions cause the upper level pins to jump upwards inside the apertures containing the pins within the lock cylinder. With a certain degree of dexterity, synchronised jumping of the upper level pins can result in all the upper level pins clearing the shear line at the same time, thereby permitting turning of the lock cylinder with respect to the lock body and hence opening of the lock.
It is therefore desirable to provide a lock assembly which will at least reduce the likelihood of unauthorised opening of a lock by way of lock bumping.